Cooling systems using refrigerant as a working fluid, such as refrigeration, freezing and air conditioning systems, are often susceptible to failure due to accumulation of moisture (water) in the refrigerant working fluid. Water vapor can enter such systems, where it is absorbed by the working fluid. In such systems, moisture accumulation can cause a host of issues, such as corrosion, acid formation, wear or breakdown of components, lower heat transfer efficiency, and other contaminant build up in the working fluid. For these reasons, monitoring of the working fluid for moisture level can be important.
Typically, a sensor system is employed that has a sight glass allowing viewing of a moisture indicator substrate exposed to the working fluid. When the substrate also is exposed to moisture, the substrate changes color. This monitoring method requires direct visual observation of the moisture indicator substrate and can prove to be ineffective where the sensor system is in a location that is hard to access, inaccessible, installed in a remote location, or not checked regularly.
Another moisture sensor system is disclosed in PCT/US1993/004747 that provides an output signal from the sensor system corresponding to the level of moisture contamination in a working fluid passing through the sensor system. The sensor system includes a cobalt bromide moisture indicator substrate that is immersed in the working fluid. An LED is used to illuminate the moisture indicator and a photodiode is used to measure the intensity of the light from the LED reflected off of the moisture indicator. The intensity is correlated to a level of moisture contamination and a corresponding signal output from the sensor system. However, the functioning of the sensor system includes numerous drawbacks including interference in the sensor system, such as contaminant in the fluid, affecting the reflected light. Other drawbacks include that the intensity of the measure reflected light typically changes with varying reflectance properties of the moisture indicator and with fluctuations in the light output of the LED, which is highly affected by temperature.